A very commonly asked question by many patients is “Doctor, Is my bypass operation going to be an open heart operation?” And my answer is ‘Yes’ and ‘No’. So what exactly is an open heart surgery? It is exactly what it means or sounds like! It’s an operation where the heart is opened! Historically, the initial cardiac or heart operations were performed for congenital heart defects. Atrial Septal defects or Ventricular septal defects (Hole in the heart) require opening of the chambers of the heart to close the hole. This can be done only if the heart is stopped. (Opening the chamber of the heart when it is beating can be disastrous!). To stop the heart, the blood from the heart is diverted to a machine which temporarily takes over the function of the heart and lungs while the surgery is performed. This machine is the ‘heart-lung machine’ or ‘the cardio-pulmonary bypass machine’. So any operation performed using this ‘heart-lung machine’ is known as an open heart operation. Coronary Artery Bypass Grafting (CABG), commonly known as ‘bypass’ operation does not involve opening of any heart chambers as the arteries to be bypassed are on the surface of the heart. However, traditionally this surgery was done by using the heart-lung machine and hence would qualify to being called a open heart operation even if no cardiac chambers are opened! Nowadays many surgeons prefer to do a beating heart bypass surgery. (I perform 90% of my bypass operations on a beating heart). Here, the heart-lung machine is not used as the heart is beating normally while the bypass is being performed. So, beating heart bypass operation should not be labelled as a open heart operation.